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inois  State  Geological  Survey 
addresses  challenges  for  a  healthy 
economy  and  a  healthy  environment 


LIBRARY. 


inois  State  Geological  Survey 
addresses  challenges  for  a  healthy 
economy  and  a  healthy  environment 


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From  the  Chief 


Research  at  the  Illinois  State  Geological 
Survey  (ISGS),  a  division  of  the  Depart- 
ment of  Energy  and  Natural  Resources 
(ENR),  strengthens  the  state's  economy  by 
encouraging  sound  exploration,  logical 
development,  and  intelligent  use  of  mineral 
resources.  At  the  same  time,  the  Survey's 
efforts  are  directed  toward  providing 
geological  information  vital  for  developing 
judicious  environmental  policies  to  protect 
and  enhance  the  health,  safety  and  well 
being  of  Illinois'  citizens. 

Earth-related  sciences  will  continue  to 
play  an  evermore  important  role  in  resolv- 
ing the  multitude  of  complex  environmental- 
and  resource-related  issues  facing  the 
state. ..nation. ..and  world.  This  annual 
report,  prepared  especially  for  the  general 
public,  presents  three  major  issues  and  the 
Geological  Survey's  research  and  service 
programs  and  projects  which  respond  to 
those  concerns.  The  period  covered  is  Fis- 
cal Year  1991,  extending  from  July  1,  1990, 
to  June  30,  1991. 

At  issue  is  the  ability  to  provide  an  ade- 
quate supply  of  domestic  petroleum  for 
transportation  fuels,  one  of  the  most 
serious  short-  and  long-term  energy 
problems  for  the  country  today.  Of  major 
concern  are  the  ongoing  developments  in 
the  oil  industry  that  have  had  a  nationwide 
impact  on  research  efforts,  domestic  oil 
production,  and  economic  development  in 
oil-producing  states.  Imports  for  the  past 
couple  of  years  have  approximated  50  per- 
cent of  the  nation's  supply  of  crude  oil  and 
petroleum  products,  placing  the  United 
States  in  a  steadily  worsening  economic 
position,  while  increasing  concerns  for 
security  of  supplies. 

While  Illinois'  oil  production  has  de- 
creased sharply  from  30  million  to  under  20 
million  barrels  of  oil  a  year,  large  quantities 


of  discovered  oil  remain  trapped  within  al- 
ready discovered  reservoirs.  Only  about 
35  percent  of  the  oil-in-place  has  been 
produced,  leaving  1 .4  billion  barrels  of  oil 
as  by-passed  mobile  oil  and  another  4.5  bil- 
lion barrels  as  residual  oil.  A  major  effort  is 
under  way  at  the  ISGS  to  find  economic 
ways  to  get  more  of  this  oil  out  of  the 
ground.  Our  scientists  are  determining 
which  methods  of  improved  recovery  work 
best  for  the  wide  range  of  conditions  exist- 
ing in  Illinois'  oil  fields.  A  segment  of  this 
report  focuses  on  this  research  and  the 
means  by  which  the  Survey  is  transferring 
the  results  and  knowledge  gained  to  the  oil 
industry  in  this  state.... 

At  issue  is  protecting  Illinois' 
groundwater  from  contamination.  The 
ISGS  is  very  actively  involved  in  meeting 
mandates  of  the  Illinois  Groundwater 
Protection  Act  by  conducting  pertinent  map- 


ping,  assessments,  monitoring,  and  techni- 
cal assistance  programs  in  support  of  the 
protection  and  preservation  of  ground- 
water's quality  as  well  as  the  management 
of  this  vulnerable  resource.  Approximately 
two-thirds  of  the  state's  population  depend 
on  groundwater  as  a  source  of  supply.  In  a 
number  of  cooperative  efforts  highlighted  in 
this  report,  the  Geological  Survey's  scien- 
tists have  been  working  to  evaluate  the  im- 
pact of  agricultural  chemicals  (pesticides 
and  nitrates)  on  groundwater,  particularly  in 
rural  areas  where  they  are  most  intensively 
used.... 

At  issue  is  the  need  for  but  absence  of 
detailed  geological  mapping  for  about  97 
percent  of  Illinois  to  address  environmental- 
and  resource-related  issues  that  face  the 
state  at  regional  and  local  levels.  Detailed 
geologic  maps  and  other  studies  of  re- 
gions, counties  or  smaller  units  provide 
state  and  regional  planners,  county  boards, 
public  health  departments  and  citizens  with 
information  about  the  Earth's  surface  and 
the  materials  that  lie  beneath  it — informa- 
tion required  to  sustain  economic  develop- 
ment and  protect  the  environment. 

Almost  every  area  of  the  state  faces 
problems  with  waste  disposal,  groundwater 
protection,  and  the  environmental  effects  of 
normal  human  activities.  Detailed  geologi- 
cal information  is  required  to  ensure  maxi- 
mum protection  from  possible  contamina- 
tion of  our  supplies  of  groundwater  and  sur- 
face water;  to  ensure  that  major  highways, 
railroads,  factories,  schools  and  other  facil- 
ities are  constructed  on  sites  that  provide 
adequate  support  for  foundations  and  are 


free  of  threats  from  flooding,  landslides, 
and  other  man-caused  and  natural  earth 
hazards;  and  to  guide  officials  in  deciding 
the  direction  of  future  economic  develop- 
ment. 

Although  much  is  known  about  the  geol- 
ogy of  Illinois  at  statewide  and  regional 
scales,  "detailed"  geological  maps  are  avail- 
able for  only  a  few  limited  areas.  Thus,  a 
program  of  detailed  geological  mapping  is 
required  to  provide  the  necessary  geologic 
information  to  cover  important  state  and 
regional  concerns.  A  segment  of  this 
report  is  devoted  to  the  mapping  needs  of 
the  state  and  the  nation  and  the  manner  in 
which  a  program  of  this  magnitude  is  at- 
tainable. 

While  this  annual  report  highlights  only 
three  issues  and  respective  ongoing  re- 
search and  service  programs  at  the  ISGS, 
the  scope  of  the  Survey's  efforts  is  far 
wider,  affecting  jobs  and  economic  growth, 
environmental  protection,  energy  security, 
access  to  minerals  and  clean  water,  ap- 
propriate use  of  land,  proper  siting  of 
facilities  and  infrastructure,  agriculture,  and 
public  safety  and  health.  For  a  more  in- 
clusive look  at  the  ISGS'  research  and  ser- 
vice pursuits,  please  request  a  copy,  free  of 
charge,  of  the  "Illinois  State  Geological  Sur- 
vey: Science  focusing  on  issues  and 
trends;  future  needs."  Should  you  wish 
more  comprehensive,  technical  informa- 
tion, I  invite  you  to  request  a  copy  of  the 
Survey's  scientific  annual  report. 


Research  Aimed  at  Improved  Oil 
and  Gas  Recovery 


Consider  the  fact  that  Illinois,  15th  in  oil  out- 
put in  the  United  States,  produced  almost 
30  million  barrels  of  oil  just  five  years  ago 
and  now  produces  just  under  20  million  bar- 
rels of  oil  a  year.  Yet,  research  at  the 
Geological  Survey  indicates  that  almost 
two-thirds  of  the  discovered  oil  remains 
trapped  within  the  reservoirs  in  the  subsur- 
face. In  fact,  the  U.S.  Department  of  Ener- 
gy (USDOE)  estimates  that  Illinois  has  6.0 
billion  barrels  of  this  unproduced  oil.  Much 
of  this  oil  is  residual,  immobile  oil  that  may 
be  produced  only  with  great  difficulty  and  at 
prices  considerably  higher  than  today's 
prices.  But  about  1 .5  billion  barrels  of  this 
unproduced  oil  remains  as  mobile,  by- 
passed oil  in  untapped  compartments  due 
to  heterogeneities  in  the  rocks  in  the  sub- 
surface. Some  of  this  oil  can  be  recovered 
using  today's  technologies  and  at  today's 


Donald  Oltz,  senior  geologist  and  head  of  the  Oil  and  Gas  Section, 
assists  Dennis  Haggerty,  petroleum  engineer,  in  taking  a  plug  from 
an  outcrop  of  the  Aux  Vases  Sandstone.  Scientists  will  study  the 
porosity,  permeability  and  other  characteristics  of  this  sample  and 
compare  them  with  geologic  information  from  subsurface  reservoirs 
in  the  same  rocks. 


prices  if  only  we  could  better  understand 
and  predict  the  factors  causing  the  com- 
partmentalization. 

Additionally,  many  wells  in  Illinois,  which 
initially  produce  hundreds  of  barrels  of  oil 
per  day,  exhibit  a  production  decline  to  less 
than  10  barrels  a  day  (a  stripper  well). 
Caused  in  some  cases  by  formation  dam- 
age, this  rate  of  decline  can  make  wells  un- 
economical and  discourages  investments. 
Improved  oil  recovery  is  possible.  It  is 
needed. 

While  Americans'  consumption  of 
hydrocarbons,  particularly  those  used  for 
transportation  fuels,  continues  its  upward 
spiral,  U.S.  production  declines — a  trend 
since  the  collapse  in  oil  prices  in  1986.  At 
an  accelerated  pace,  major  U.S.-based  oil 
companies  are  shipping  their  capital  for  ex- 
ploration and  development  overseas.  Tens 
of  billions  of  dollars  that  once  would  have 
been  spent  to  drill  wells  or  build  refineries 
in  this  country  are  being  earmarked  for 
foreign  operations.  According  to  an 
analysis  of  18  domestic  companies  by 
Petroleum  Finance  Co.,  the  U.S.  share  of 
all  their  spending  for  exploration  and 
development  dropped  from  60  percent  in 
1 985  to  20  percent  in  1 990.  Inevitably,  the 
result  will  be  a  further  decline  in  domestic 
oil  production  and  increased  dependence 
on  imports,  not  just  for  crude  oil  but  for 
refined  products  such  as  gasoline  and  jet 
fuel  as  well.  Estimates  indicate  this  country 
will  import  an  average  of  47  percent  of  its 
oil  and  gas  in  1992. 

While  this  trend  will  continue,  geological 
investigations  have  shown  that  some  things 
can  be  done  at  home  to  reduce  the  rate  of 
decline  and  help  in  the  event  of  another  oil 
crisis.  Work  by  the  Illinois  State  Geological 
Survey,  now  in  the  third  year  of  a  program 
designed  to  increase  Illinois'  oil  resources 


and  prudently  develop  them,  has  con- 
tributed to  the  results  of  these  investiga- 
tions. This  program  of  improved  oil 
recovery  has  been  recognized  as  fitting  in 
well  with  the  objectives  of  the  National 
Energy  Strategy,  which  emphasizes  the 
domestic  oil  supply  and  a  reduction  of  im- 
ports. 

To  help  increase  oil  recovery  and  aid 
economic  development  of  the  depressed  oil 
industry  in  the  state,  the  ISGS  has  an  in- 
tegrated, multidisciplinary  team  of  geol- 
ogists, reservoir  engineers,  geochemists, 
clay  mineralogists,  and  computer  experts 
analyzing  and  assessing  oil  reservoirs  and 
studying  the  impact  of  reservoir  heteroge- 
neity on  oil  production.  Goals  of  this  major 
effort  are  to  aid  Illinois'  independent  oil 
producers  in  the  recovery  of  higher  percent- 
ages of  oil  from  fields  already  discovered, 
develop  new  incentives  to  encourage  ex- 
ploration, promote  logical  development  of 
Illinois'  oil  and  gas,  and  provide  relevant 
and  timely  information  to  the  oil  industry 
and  the  public  through  technology  trans- 
fer— a  major  component  of  the  project. 
Through  outreach  programs  and  work- 
shops, which  have  already  begun,  re- 
searchers hope  to  encourage  producers  to 
apply  promising  techniques  in  drilling,  com- 
pleting, maintaining  and  managing  reser- 
voirs to  maximize  hydrocarbon  recovery. 

Program  heralded,  studies 

15  fields 

Representatives  from  industry  and  the 
USDOE  have  heralded  the  Geological 
Survey's  four-year,  $4.9  million  program  as 
a  model.  This  matching  state-federal 
cooperative  venture  is  already  providing  in- 
formation on  hydrocarbon  resources,  reser- 
voir characteristics,  production  methods 
and  reservoir  management.  Researchers 
have  made  substantial  progress  in  their 
pilot  studies  of  the  type  and  degree  of  reser- 
voir heterogeneity  in  15  fields  producing 
from  two  of  Illinois'  most  prolific  oil-produc- 
ing horizons,  the  Cypress  and  Aux  Vases 
formations,  and  have  already  begun  to 
publish  their  results. 

To  unlock  the  secrets  to  more  efficient 
oil  recovery  in  these  horizons,  the  geol- 
ogists are  using  many  "tools"— from  simple 
saws,  grinders,  and  drills  to  seismic  ex- 
perimentation and  a  multitude  of  sophisti- 
cated instruments,  including  testing 
equipment,  simulators,  and  workstations 
providing  computerized  graphics.  Through 
thorough,  intensive  probings  in  the  field 
and  laboratory  or  at  a  computer  and  draft- 
ing table,  they  are  getting  a  foothold  on 


Petroleum 
geologist  Bob 
Cole  labels  a 
core  sample 
of  Cypress 
sandstone. 


potential  problems  and  conditions  within 
reservoirs  capable  of  impeding  recovery  of 
Illinois'  oil. 

To  achieve  a  greater  understanding  of 
the  hydrocarbon  reservoirs,  staff  members 
have  also  undertaken  an  investigation  of 
the  features  found  in  these  same  rock  inter- 
vals exposed  at  the  surface.  They  com- 
pleted a  statewide  surface  investigation  of 
the  Aux  Vases  Formation  in  1990  and  sub- 
sequently began  a  similar  investigation  on 
the  Cypress  Formation  wherein  the  re- 
searchers are  recording  detailed  observa- 
tions and  measurements  and  collecting 
samples  for  microscopic  and  other  evalua- 
tions; thereafter,  the  geologist  responsible 
for  compiling  the  information  is  interpreting 
results. 

In  one  specific  aspect  of  this  study,  the 
scientists  are  making  a  highly  detailed  in- 
vestigation of  an  extensive  Cypress  out- 
crop located  on  Interstate  57  near  Anna. 
They  are  treating  this  outcrop  as  an  analog 
of  a  petroleum  reservoir,  gathering  informa- 
tion on  an  inch-by-inch  basis.  The  scien- 
tists are  describing  the  exposure  in  great 
detail  and  using  sophisticated  instrumenta- 
tion to  determine  the  permeability  of  the 
rocks  (a  measure  of  the  ability  of  fluids  to 
move  through  the  rocks)  as  well  as  the 
amount  of  low-level  gamma  ray  emissions 
from  the  rocks  (indicative  of  how  clean  the 
sands  are).  With  a  high-powered  drill,  they 
are  also  taking  samples  for  further  testing 
in  the  laboratory.  Results  are  then  being 
compared  with  similar  information  gathered 
from  selected  oil-producing  horizons  in  the 
subsurface. 

In  addition,  staff  members  are  compiling 
data  from  chosen  wells  in  the  oil-producing 
area  of  the  state  to  be  used  in  a  regional 
study  of  the  relationships  among  outcrops, 


subsurface  stratigraphy  and  hydrocarbon 
reservoirs.  Cross  sections,  showing 
stratigraphic  changes  within  these  forma- 
tions, and  maps,  showing  reservoir  distribu- 
tion, will  be  constructed. 

Technologies  extrapolated 
to  similar  reservoirs 

The  Survey's  geologists  are  also  studying 
the  composition  of  a  reservoir  using  core 
samples  examined  by  X-ray  diffraction  to 
determine  the  kinds  and  relative  quantities 
of  clay  minerals  present,  which  are  often 
troublesome  in  oil  recovery,  and  a  Scan- 
ning Electron  Microscope  to  determine  the 
distribution  and  shape  of  pores  in  the  rocks 


Steve  Sim,  petroleum  engineer,  demonstrates  a  new  state-of-the  art 
pressure,  volume  and  temperature  (PVT)  apparatus  that  simulates 
oil-production  conditions  in  the  laboratory.   When  oil  is  brought  to  the 
surface,  a  change  in  pressure,  volume  and  temperature  causes 
some  oil  loss  in  the  form  of  gas.  The  ISGS  can  help  oil  producers 
calculate  this  loss  with  PVT  equipment,  which  measures  the  de- 
crease in  the  volume  of  oil  as  it  comes  to  the  surface  and  the  amount 
of  gas  released  at  the  surface.   With  the  PVT,  researchers  can  simu- 
late carbon  dioxide  injections  (used  to  enhance  oil  recovery)  and 
measure  oil  swelling  and  viscosity  reduction  at  reservoir  temperature 
and  pressure  and  calculate  the  potential  increase  in  production. 
Fluid  analysis  data  are  useful  for  estimating  oil  and  gas  reserves  in 
the  reservoir,  designing  surface  oil  and  gas  separation  equipment, 
planning  production  strategy  and  for  enhanced  oil  recovery. 

comprising  the  reservoir.  Regionally,  they 
are  correlating  these  analyses  with  inter- 
pretations of  similarities  in  depositional 
processes,  reservoir  geometries,  and 
wireline  log  responses  of  reservoir  rocks. 
To  date,  results  indicate  that  similar 
modifications  during  and  after  deposition 
are  responsible  for  development  of  reser- 
voir characteristics  in  the  Aux  Vases  over 
specific  areas  being  studied.  Knowledge  of 
reservoir  similarities  will  permit  testing  and 


subsequent  extrapolation  of  specific  tech- 
nologies for  improving  oil  recovery  to  other 
reservoirs. 

Knowing  the  type  of  rock  and  clay 
minerals  and  their  areal  distributions  across 
a  reservoir  are  important  factors  for 
developing  an  optimal  recovery  system. 
Researchers  have  detected  significant  dif- 
ferences in  clay  content,  types  of  clay 
minerals  and  cementing  minerals  that  af- 
fect a  well's  productivity  and,  therefore, 
should  be  considered  during  drilling  and 
completion.  For  instance,  clays  subjected 
to  a  fresh-water  drilling  mud  may  swell  and 
plug  rock  pores,  cutting  off  porosity  and  per- 
meability, thereby  diminishing  oil  recovery. 
In  addition,  acids,  normally  used  to  stimu- 
late production  or  remove  excess  casing  ce- 
ment, can  also  harm  recovery  by  reacting 
with  certain  clay  minerals.  Clay-mineral 
particles,  when  dislodged,  can  plug  up 
pores.  Forewarned,  a  producer  can  take 
appropriate  measures  while  developing  a 
reservoir/field. 

Using  other  state-of-the-art  apparatus, 
researchers  in  the  ISGS'  laboratories  are 
flooding  core  samples  from  reservoirs  with 
hydrochloric  acid,  different  brines,  fresh 
water,  or  other  chosen  fluid  desired  and  are 
studying  reactions  to  determine  any  pos- 
sible mischief  these  substances  can  cause 
in  a  given  reservoir.  The  fluids  chosen  for 
this  research  effort  simulate  those  normally 
used  in  Illinois'  oil  fields.  Then  too,  staff 
members  are  looking  at  reservoir  fluids  to 
predict  reactions  that  influence  porosity  and 
permeability  and  changes  in  reservoir  prop- 
erties in  response  to  the  injection  of  fluids 
used  in  enhanced  oil  recovery.  During  this 
period,  they  have  collected  39  samples  of 
brine  and  oil  from  the  Aux  Vases  and  Cy- 
press formations  and  are  analyzing  them 
for  various  physical  and  chemical  attri- 
butes. The  data  will  be  used  for  computer 
modelling  to  forecast  formation  damage 
from  the  use  of  certain  fluids. 

In  other  experiments,  also  under  simu- 
lated reservoir  conditions,  researchers  vary 
pressure,  volume  and  temperature  of  dif- 
ferent oils  to  learn  the  optimal  parameters 
for  estimating  oil  and  gas  reserves  and 
planning  production  strategies  as  well  as 
for  enhanced  oil  recovery  studies  such  as 
the  effects  of  injecting  carbon  dioxide  into  a 
reservoir. 

Visuals  (a  variety  of  geologic  maps, 
cross  sections,  well  logs,  photos  of  mineral 
deposits  taken  from  microscopic/analyzer 
examinations  of  core  samples,  three- 
dimensional  computer  modelling  of  the 
subsurface,  etc.)  are  very  important  to  this 


This  three-D 
display  shows 
changes  in  pres- 
sure in  the  oil- 
producing 
formation  over  a 
period  of  time. 


research,  allowing  observations  of  the 
many  complexities  within  a  reservoir. 
Computer  imaging  capabilities  permit  re- 
searchers to  see  a  reservoir  take  shape 
layer  by  layer,  study  the  distribution  of  the 
sands,  strip  away  non-reservoir  rock,  and 
filter  information  any  way  they  choose.  In 
fact,  with  such  a  graphic  tool,  they  can  strip 
out  the  characteristics  desired,  move  them 
into  a  reservoir  simulator,  simulate  a  water 
flood  with  wells  at  various  spacings,  and  ob- 
serve the  results — all  from  their  worksta- 
tions at  the  ISGS. 

Thus  far,  the  Survey's  geologists  have 
defined  the  types  of  reservoirs  and  charac- 
teristics of  each,  looked  beyond  deposition- 
al  environments  to  post-depositional  factors 
that  have  affected  the  reservoirs,  and  are 
learning  how  characteristics  affect  recovery 
of  hydrocarbons.  Because  of  compartmen- 
talization,  they  have  confirmed  a  need  to 
alter  Illinois'  10-acre  well  spacing  when  by- 
passed oil  can  be  ascertained  by  geologic 
and  engineering  studies.  The  scientists 
have  documented  that  clays  are  important 
factors  within  these  reservoirs.  Major 


Using  the  new  Silicon 
Graphics  workstation, 
Emmanuel  Udegbunam, 
petroleum  engineer,  at 
left,  and  Hannes  Leetaru, 
petroleum  geologist,  take 
the  results  of  oil-field 
studies  into  the  next  re- 
search phase:  modelling 
reservoir  characteristics 
and  production  data  via 
three-dimensional  color 
graphics. 


players  in  reservoir  damage,  clay  minerals, 
if  not  handled  properly,  are  often  detrimen- 
tal to  the  recovery  of  oil. 

Focused  studies,  results 

Examples  of  the  results  to  date  are 
provided  by  the  following  brief  reviews  of  in- 
tegrated studies  of  the  Tamaroa,  Bartelso 
and  King  fields.  Tamaroa  Field,  which 
produces  from  the  Cypress  Sandstone,  has 
been  studied  to  evaluate  the  potential  to  in- 
crease its  cumulative  oil  production  and 
define  recovery  problems.  Discovered  in 
1942,  this  field,  located  in  northeast  Perry 
County,  produces  just  below  1 ,100  feet, 
principally  from  multiple  lenticular  stacked 
sandstones,  separated  by  shales.  Based 
on  records  of  32  of  the  46  producing  wells, 
the  Tamaroa  and  Tamaroa  South  fields 
produced  some  770,000  barrels  through 
1989,  but  only  a  few  wells  in  Tamaroa 
South  remain  in  operation  today. 

Comparison  of  the  separate  pools  in  this 
area  shows  similarities  in  the  physical  char- 
acteristics of  the  sandstone  bodies.  Scien- 
tists believe  the  depositional  processes  and 
settings  for  the  sandstones  were  also  likely 
similar.  Intuitively,  one  might  expect  similar 
recovery  efficiencies,  but  this  has  not  been 
the  case. 

Within  the  multiple  oil  reservoirs  of  the 
Tamaroa  and  Tamaroa  South  fields,  both 
marginal  and  successful  production  pro- 
grams are  apparent.  Efficiencies  in  recov- 
ery have  varied  widely.  For  example,  the 
Tamaroa  Field,  developed  in  two  stages, 
had  recovery  efficiencies  of  five  percent  in 
the  initial  wells  (attributable,  in  part,  to 
release  of  gas  pressure  from  the  reservoir) 
to  43  percent,  achieved  by  primary  (pump- 
ing) and  coordinated  secondary  (water 
flooding)  recovery  methods.  Tamaroa 


South,  also  developed  in  two  stages, 
achieved  25  and  32  percent  efficiencies 
using  some  water  flooding. 

The  variable  recovery  is  a  result  of  reser- 
voir heterogeneity,  an  understanding  of 
these  complexities,  and  the  subsequent 
manner  in  which  these  fields  have  been 
managed.  Reservoir  management  should 
be  a  combined  program  through  all  stages 
of  drilling,  completion,  stimulation  and 
development.  Research  indicates  that 
more  can  be  done  to  wisely  produce  these 
fields....  The  study  found  that  improved  oil 
recovery  techniques  can  increase  produc- 
tion for  the  field  by  using  developmental 
drilling;  pressure  maintenance;  coordinated 
secondary  (water  flood)  recovery  pro- 
grams; and  where  compartmentalization 
exists,  different  well-spacing  practices. 

Bartelso's  development 
well  managed 

Another  study  detailing  the  rocks  and  struc- 
tural factors  that  affect  reservoir  develop- 
ment and  hydrocarbon  recovery  from 
sandstones  in  the  Cypress  Formation  is 


In  the  geologic  model,  a  three-dimensional  grid  of  cross  sec- 
tions (fence  diagrams)  is  superimposed  on  a  projection  of 
wells  drilled  into  the  Aux  Vases  Sandstone,  an  oil-bearing 
reservoir.  Rotating  the  grid,  petroleum  geologists  can  change 
the  perspective  of  the  subsurface  rock  formations,  and  using  a 
zoom  control,  they  can  look  at  by-passed  portions  of  the  forma- 
tions from  which  the  oil  has  not  been  recovered. 

that  of  the  Bartelso  Field,  discovered  in 
1936,  in  south-central  Clinton  County.  The 
management  of  this  field  represents  a  suc- 
cess story  inasmuch  as  50  percent  (about 
2.5  million  barrels)  of  the  oil  has  been  ex- 
tracted from  76  wells  compared  to  one-third 
efficiency  of  recovery  achieved  by  employ- 
ing normal  primary  and  secondary  produc- 


tion methods  in  most  reservoirs  in  the  Il- 
linois Basin.  Well-coordinated  water  flood- 
ing covering  multiple  leases  throughout  the 
entire  reservoir  and  varied  well  spacing 
were  key  elements  in  the  high  level  of 
recovery  at  Bartelso. 

The  upper  sandstones  in  the  Cypress  at 
Bartelso  are  shingled  bars  and  the  primary 
reservoir.  The  Cypress  in  that  field  has 
been  subdivided  into  four  separate  sand- 
stone intervals,  the  upper  three  of  which 
contain  oil  and  gas.  Researchers  have 
found  that  only  the  lowermost  producing 
sandstone  exhibits  sufficient  homogeneity 
to  be  efficiently  drained  with  a  10-acre  well 
spacing.  Because  of  the  complexities  in 
the  upper  two  producing  units,  closer  well 
spacing  was  needed  to  optimize  recovery. 

Illinois'  10-acre  well  spacing  for  sand- 
stone reservoirs  was  arbitrarily  established 
with  no  geologic  basis.  Reservoirs  deeper 
than  4,000  feet  require  an  arbitrary  20-acre 
spacing,  according  to  regulations.  Such 
spacing  criteria  are  waived  with  water  flood- 
ing, allowing  tighter  spacing  at  Bartelso, 
where  compartmentalized  oil  in  the  upper 
two  producing  units  would  have  been 
missed  otherwise.  This  study,  in  itself, 
points  out  the  need  for  strategic  infill  drilling 
based  on  geology  rather  than  arbitrary 
spacing. 

Looking  at  the  Survey's  study  of  the 
King  Field,  one  learns  that  the  productive 
Aux  Vases  sandstone  was  formed  in  a 
nearshore,  marine  environment  similar  to 
the  Bartelso  Field.  The  King  Field,  located 
five  miles  southeast  of  Mt.  Vernon,  in  Jeffer- 
son County,  extends  over  1 ,700  acres.  It 
produces  mainly  at  a  depth  of  about  2,750 
feet,  although  there  is  minor  production 
from  overlying  and  underlying  reservoirs. 
From  the  original  17  million  barrels  of  oil  in 
place,  108  wells  have  produced  4.1  million 
barrels  since  1942. 

Although  depositional  environments 
were  similar  between  the  King  and  Bartelso 
fields,  their  efficiencies  of  recovery  are 
quite  different,  King  having  less  than  30  per- 
cent versus  the  50  percent  attained  at  Bar- 
telso. 

Post-depositional  alterations  occurred  in 
the  King  reservoir,  causing  a  high  degree 
of  reservoir  heterogeneity.  Chemical 
properties  of  the  rock  reservoir  were  al- 
tered. For  instance,  scientists  found  more 
clay  and  calcite  in  the  reservoir  at  King 
than  Bartelso.  Calcite  cement  and  clay 
made  recovery  of  oil  from  the  King  Field 
more  difficult.  These  influences  on  reser- 
voir heterogeneity  as  well  as  compart- 
mentalization resulting  from  depositional 


conditions  were  not  understood  when 
recovery  methods  were  applied. 

As  production  steadily  declined  after 
1966,  there  were  no  new  water  floods,  out- 
posts or  infill  wells.  In  fact,  most  of  the 
wells  were  plugged  and  abandoned  after 
the  collapse  of  oil  prices  in  1986. 

Significant  areas  unswept 

Abandonment  may  have  been  premature, 
according  to  the  Survey's  researchers. 
Their  study  shows  that  compartmentaliza- 
tion  in  the  reservoir  at  King  Field  has  al- 
lowed significant  areas  to  remain  unswept 
by  recovery  efforts  using  water  flooding. 
An  estimated  one  to  two  million  barrels  of 
oil  may  be  recoverable  by  primary  and 
water-flood  methods.  Data,  which  will  help 
implement  improved  or  enhanced  oil 
recovery  techniques  in  this  oil  field,  and 
areas  where  these  techniques  should  be 
applied  are  presented  in  a  report  already 
released  by  the  ISGS  entitled  "Reservoir 
Heterogeneity  and  Improved  Oil  Recovery 
of  the  Aux  Vases  (Mississippian)  Formation 
at  King  Field,  Jefferson  County,  Illinois." 

Scientists  at  the  Geological  Survey 
believe  that  geologically-targeted  infill  drill- 
ing between  existing  wells  combined  with 
selective,  well-designed  water  flooding  may 
be  able  to  recover  up  to  1 5  percent  of  the 
remaining  primary  reserves  in  the  King 
Field. 

Based  upon  such  current  studies,  the 
Illinois  State  Geological  Survey  is  develop- 
ing an  understanding  of  reservoir  hetero- 
geneities and  the  implications  of  reservoir 
management  to  handle  these  variations. 
Through  seminars,  workshops,  poster  ses- 
sions, and  invited  talks,  staff  members  are 
already  sharing  much  of  this  new  know- 
ledge with  those  who  can  put  it  to  good  use 
in  the  oil  fields.  Such  technology  transfer 
to  operators  and  other  representatives  of 


Technology  transfer  is  pic- 
tured with  Kenneth  McGee, 
petroleum  geologist,  pointing 
out  a  Cypress  Sandstone 
reservoir  to  an  oil  producer. 
During  a  workshop,  scientists 
presented  and  displayed  in- 
termediate results  of  field 
studies  on  the  Cypress  and 
Aux  Vases  formations  in  the 
Illinois  Basin  to  independent 
oil  producers. 


the  oil  industry  in  Illinois  has  occurred  a 
number  of  times  during  this  reporting 
period.  The  scientists  presented  invited 
talks  describing  this  research  to  members 
of  the  Illinois  Oil  and  Gas  Association,  Il- 
linois Oil  Producers  Association,  the  Ken- 
tucky Oil  and  Gas  Association,  the  Illinois 
Stripper  Well  Owners  and  Royalty  Associa- 
tion, the  Eastern  Section  of  the  American 
Association  of  Petroleum  Geologists 
(AAPG),  the  Fifth  International  Archie  Con- 
ference, and  the  Illinois  Geological  Society. 

In  addition,  the  researchers  have  pre- 
sented poster-style  displays,  showcasing 
their  work  at  the  Illinois  Oil  and  Gas  Asso- 
ciation's annual  meeting,  attended  by  some 
400  local  geologists,  oil  company  opera- 
tors, and  service  company  representatives. 
Exhibits  were  also  presented  at  the 
AAPG's  national  meeting,  attended  by 
more  than  6,000  national  and  international 
representatives  of  the  petroleum  industry, 
and  the  Eastern  Section  meeting  of  AAPG. 

The  payoff  for  employing  enhanced 
recovery  techniques  suggested  by  this  re- 
search is  handsome.  Consider  the  fact 
that  the  state's  1 990  oil  production  of 
1 9,900,000  barrels  had  a  value  of  more 
than  $398  million  at  $20  a  barrel.  Of  the  es- 
timated 6.0  billion  barrels  of  by-passed  oil 
left  in  reservoirs  across  the  state,  some  1 .5 
billion  barrels  represent  mobile  recoverable 
oil.  If  the  application  of  technology 
developed  during  this  program  resulted  in 
an  increased  production  of  1 0  percent  of 
these  1 .5  billion  barrels  of  unswept  mobile 
oil,  at  $20.00  a  barrel,  the  value  of  in- 
cremental production  in  Illinois  could  equal 
$3.0  billion.... 

And  if  the  application  of  this  technology 
opened  up  Illinois'  oil  fields,  other  positive 
ramifications  would  accrue  such  as  an  im- 
proved economy  in  the  depressed  oil-field 
areas  of  Illinois. 


Protection  Crucial  to  Groundwater's 
Quality,  Usability 


Water,  although  a  necessity  for  all  living 
things,  is  also  a  key  to  future  economic 
growth.  While  its  use  in  this  country  over 
the  past  40  years  has  more  than  doubled, 
this  vital  resource  has  been  and  remains 
very  vulnerable  to  contamination. 

Will  there  be  water  for  future  genera- 
tions? Will  it  be  suitable  for  consumption? 
How  will  water  be  protected  from  human  ac- 
tivities that  could  be  spoiling  its  use? 

While  not  fully  funded,  the  Illinois 
Groundwater  Protection  Act  mandates  ac- 
tivities that  will  provide  information  to  help 
balance  protection  and  use  of  the  ground- 
water resource.  It  calls  for  developing  a 
coordinated  groundwater  data  collection 
and  automation  system,  including  results  of 
groundwater  monitoring  and  collection  of 
well  logs,  pollution  source  permits,  and 
water  quality  assessments;  developing  and 
administering  ongoing  basic  and  applied  re- 


search; and  making  results  and  information 
available  to  local  governments  seeking  as- 
sistance. Activities,  to  be  carried  out  by  the 
Department  of  Energy  and  Natural  Resour- 
ces (ENR),  of  which  the  ISGS  is  a  division, 
include  the  following: 

1 .  long-term  statewide  groundwater  moni- 
toring; 

2.  statewide  assessments  of  groundwater 
resources  to  enhance  the  data  base  by 
locating  resources,  mapping  aquifers,  iden- 
tifying appropriate  recharge  areas,  and 
evaluating  base  line  water  quality; 

3.  evaluating  the  impact  of  pesticides  on 
groundwater;  and 

4.  other  basic  and  applied  research,  includ- 
ing groundwater  hydrology  and  hydraulics, 
movement  of  contaminants,  and  technolo- 
gies for  the  restoration  and  remediation  of 
aquifers. 


On  the  left,  Dennis  McKenna,  geologist  in  the  Ground- 
water Protection  Section,  uses  a  baler  to  remove 
groundwater  samples  from  a  monitoring  well  located 
next  to  a  stream.  Above,  he  purges  the  monitoring  well 
before  obtaining  a  fresh  sample  that  is  more  repre- 
sentative of  the  water  found  in  the  aquifer. 


For  their  study  of  groundwater's  contamination  by  atrazine,  scientists  found  this  farm  south  of  Urbana  that  met  all 
of  their  criteria:  corn  and  soybeans  in  rotation,  presence  of  a  tile-drainage  system,  past  and  current  use  of 
atrazine,  relatively  uniform  soil  and  geologic  conditions,  co-location  with  existing  water  quality  studies  by  state  or 
federal  agencies,  and  cooperation  of  the  landowner. 


Among  programs  that  have  received 
funding  are  ones  investigating  the  impact  of 
pesticides  on  groundwater  and  ground- 
water assessments.  Concern  over  the 
potential  for  contamination  of  groundwater 
by  agricultural  chemicals  is  founded  on  the 
following  facts: 

•  Two  out  of  three  acres  of  rural  Illinois 
are  treated  with  agricultural  chemi- 
cals— some  50  million  pounds  of  pes- 
ticides and  a  million  tons  of  nitrogen 
fertilizer  annually. 

•  More  than  80  percent  of  the  corn  and 
nearly  30  percent  of  the  soybean 
acreage  receiving  preplant  or  preemer- 
gent  weed  control  in  1 990  was  treated 
with  herbicides  that  pose  a  potential 
hazard  to  groundwater  in  vulnerable 
soil  and  hydrogeologic  settings. 

•  Groundwater  is  the  only  source  of 
drinking  water  for  about  97  percent  of 
the  rural  population  in  this  state. 

•  Aquifers  occur  within  50  feet  of  the 
ground's  surface  in  about  40  percent 
of  rural  Illinois. 

•  State  and  county  agencies  have 
detected  pesticides  in  samples  of 
groundwater  from  shallow  aquifers. 
However,  public  water  wells  that  nor- 
mally withdraw  water  from  deep 
aquifers  apparently  have  not  been 
significantly  affected. 

Thus,  accurate  prediction  of  the  vulner- 
ability of  groundwater  resources  to  contam- 


ination from  agricultural  chemicals  (pesti- 
cides and  nitrates)  is  one  of  the  most  impor- 
tant environmental  issues  facing  farmers, 
water  users  and  governmental  agencies. 
With  current  agricultural  practices  and  tech- 
nology, leaching  of  agricultural  chemicals— 
particularly  nitrates  derived  from  fertilizer 
nitrogen  and  the  more  mobile  pesticides — 
into  groundwater  may  be  impossible  to 
prevent.  Areas  most  vulnerable  to  con- 
tamination must  be  identified  to  effectively 
target  educational  programs,  technical  as- 
sistance, and  detailed  monitoring  studies  of 
groundwater  resources  in  the  state. 

Regulation  of  the  use  of  agrichemicals 
must  also  take  into  account  the  vulnerabil- 
ity of  groundwater  resources.  The  USEPA 
has  published  a  strategy  to  regulate  the 
use  of  pesticides  to  prevent  unacceptable 
levels  of  contamination  in  current  and  po- 
tential supplies  of  drinking  water.  It  recom- 
mends managing  the  use  of  pesticides  on 
the  basis  of  differences  in  the  use  of  ground- 
water, its  value  and  vulnerability.  The  agen- 
cy also  recommends  using  the  vulnerability 
of  groundwater  as  a  basis  for  county-  or 
state-level  measures,  which  may  include 
cancelling  the  use  of  specific  products. 

If  water  is  under  protected,  it  may  be- 
come contaminated,  detrimentally  affecting 
users.  On  the  other  hand,  over  protection 
of  this  resource  could  result  in  restrictions 
in  areas  that  do  not  require  stringent  protec- 
tive measures,  resulting  in  economic  hard- 
ship. Thus,  an  optimum  level  of  protection 
for  groundwater  should  balance  the  use  of 


11 


12 


agricultural  chemicals  and  protective  meas- 
ures. Research  relating  to  the  effects  such 
chemicals  are  having  on  Illinois'  aquifers  is 
under  way  at  the  ISGS. 

In  support  of  the  state's  Pesticide  Man- 
agement Plan  being  developed  by  the  Illi- 
nois Department  of  Agriculture  (IDOA),  the 
Geological  Survey's  scientists  are  using 
knowledge  of  groundwater  flow,  soil  and 
rock/water  interaction,  and  statewide  geo- 
logic maps  to  identify  regions  with  aquifers 
vulnerable  to  contamination  by  agricultural 
chemicals. 

Precipitation, 

source  of  groundwater 

Illinois'  source  of  groundwater  is  precipita- 
tion that  infiltrates  the  soil  and  percolates 
downward  to  the  water  table.  The  replenish- 
ment of  groundwater,  known  as  recharge, 
depends  upon  the  moisture  conditions  of 
soil,  its  permeability  and  water  retention 
capacity,  type  and  distribution  of  vegeta- 


Zhenkun  Zhao,  left,  and  Lettie  Schmitt,  both  lab  assistants  in  the  Geo- 
logical Survey's  Environmental  Geology  Laboratory,  are  measuring 
the  uptake  of  pesticides  by  soil. 

tion,  duration  and  intensity  of  precipitation, 
and  location  within  the  groundwater-flow 
system.  Regionally,  the  interrelationship  of 
surface  soils,  underlying  geologic  materials, 
and  configuration  of  the  landscape  deter- 
mines the  rate  and  amount  of  recharge  and 
the  direction  of  shallow  groundwater  flow. 
Tile-drainage  systems  in  agricultural  areas 
may  alter  natural  drainage  and  recharge. 
Recharge  does  not  occur  at  specific  points 
or  in  small  areas;  some  recharge  occurs  in 
all  unpaved  areas  except  the  discharge 
areas.  Streams  in  Illinois  that  flow  all  or 
most  of  the  year  are  groundwater-discharge 


areas.  Water  will  infiltrate  to  the  water 
table  over  the  entire  interstream  area; 
some  water  will  move  upward  through 
evaporation  from  the  soil  and  transpiration 
from  plants,  while  the  remainder  will  move 
downward  into  the  saturated  zone.  Some 
of  this  water  will  discharge  into  nearby 
streams  with  the  remainder  moving  deeper 
into  the  regional  groundwater-flow  system. 

The  movement  of  groundwater  is  direct- 
ly related  to  the  permeability  of  geologic 
materials  and  the  hydraulic  gradient.  In 
areas  directly  underlain  by  permeable  bed- 
rock or  sand  and  gravel,  relatively  rapid  in- 
filtration and  movement  will  occur.  How- 
ever, in  areas  underlain  by  silty  or  clayey 
materials,  surface  runoff  may  be  greater 
and  the  movement  of  groundwater  general- 
ly slower,  providing  considerably  less 
recharge  to  aquifers  than  in  areas  com- 
posed of  sand  and  gravel  or  permeable 
bedrock  at  or  near  the  surface.  Thus,  the 
vulnerability  of  an  aquifer  is  estimated  on 
the  basis  of  the  thickness  and  character  of 
materials  overlying  it.  The  character  of  the 
materials  affects  the  rate  of  movement  and 
the  degree  of  attenuation  (reduction  in  the 
concentration  of  a  pesticide);  the  thickness 
affects  the  time  to  reach  an  aquifer,  allow- 
ing more  time  for  attenuation. 

For  the  project  with  IDOA  on  identifying 
regions  with  aquifers  vulnerable  to  con- 
tamination from  agricultural  chemicals,  the 
Survey  has  mapped  Illinois  at  a  scale  of 
1 :500,000  (one  inch  equals  approximately 
eight  miles).  It  is  also  providing  county 
maps  developed  at  1:250,000  (one  inch 
equals  approximately  four  miles).  A  report 
will  accompany  each  map  and  summarize 
the  factors  and  processes  affecting  the 
transport  of  agricultural  chemicals  to 
groundwater  resources. 

The  interpretive  maps  are  based  on  the 
distribution  of  the  Earth's  materials.  Highly 
permeable  materials  (sands,  gravels,  frac- 
tured carbonate  rocks,  and  sandstones)  will 
generally  allow  rapid  migration  of  contamin- 
ants. Materials  of  relatively  low  permeability 
(loess,  glacial  till,  shales,  cemented  sand- 
stone, and  unfractured  carbonate  rocks) 
generally  restrict  contaminant  migration. 
Thickness  of  fine-grained  materials  controls 
the  susceptibility  of  the  underlying  aquifers 
to  contamination;  the  thicker  the  sequence 
of  fine-grained  material  between  the  source 
and  the  aquifer,  the  less  likely  the  aquifer 
will  become  contaminated.  In  addition,  the 
concentration  of  a  chemical  may  be  re- 
duced by  natural  processes  (degradation, 
dilution,  adsorption)  before  it  reaches  an 
underlying  aquifer. 


In  the  Environ- 
mental Geology 
Laboratory,  Bill 
Roy,  geochemist, 
examines  an  ex- 
tract of  a  soil 
sample. 


Distribution  of 
geologic  deposits 

To  map  the  potential  for  contamination  of 
aquifers  by  agricultural  chemicals,  scien- 
tists used  geologic  information  compiled 
from  the  Stack-Unit  Map  of  Illinois  publish- 
ed in  1988  by  the  ISGS.  (The  mapped 
units  depict  the  distribution  of  geologic  de- 
posits vertically  from  the  surface  to  a  depth 
of  50  feet  as  well  as  horizontally  over  a 
specified  area.)  Staff  members  combined 
sequences  of  materials  into  four  groups  dif- 
ferentiated on  the  basis  of  distance  from 
the  land's  surface  to  the  top  of  the  first  con- 
tinuous deposit  of  aquifer  materials.  In 
addition  to  the  nature  of  earth  materials, 
other  factors,  including  the  amount  and 
properties  of  a  given  chemical  and  climatic 
factors,  also  need  to  be  considered  in  deter- 
mining the  ultimate  potential  for  contamina- 
tion. 

According  to  the  maps  and  report  pre- 
pared for  the  study  entitled  "Potential  for 
Agricultural  Chemical  Contamination  of 
Aquifers  in  Illinois,"  areas  with  intensive 
corn  and  soybean  production  and  aquifer 
materials  within  50  feet  of  the  Earth's  sur- 
face are  most  vulnerable  to  contamination. 
Scientists  based  this  interpretation  on  their 
present  understanding  of  the  persistence  of 
pesticides  and  rates  of  groundwater  move- 
ment coupled  with  the  results  of  studies  on 
pesticides  made  in  Iowa  and  Minnesota, 
which  showed  that  pesticides  were  most 
commonly  detected  in  shallow  aquifers. 

In  approximately  40  percent  of  rural 
Illinois,  aquifers  lie  within  50  feet  of  the 
ground's  surface.  These  shallow  aquifers 
occur  throughout  the  state  but  are  most 
common  in  the  northern  and  southern  parts 


Phil  Reed,  geologist  in  the  Hydrogeology  Sec- 
tion, lowers  a  sonde  into  an  observation  well 
to  determine  the  sequence  of  earth  materials. 

and  along  the  major  river  valleys.  In  about 
60  percent  of  Illinois'  rural  areas,  aquifers 
are  more  than  50  feet  deep  and  apparently 
protected  from  contamination  by  agricul- 
tural chemicals  by  the  attenuation  capacity 
(all  physical,  chemical  and  biological  pro- 
cesses that  reduce  the  concentration  of  a 
pesticide)  of  soils  and  thick  sequences  of 
fine-grained  materials.  The  use  of  pesti- 
cides, largely  for  corn  and  soybean  produc- 
tion, is  heaviest  in  areas  of  Illinois  where 
aquifers  are  generally  least  vulnerable  to 
contamination.... 

Additionally,  in  response  to  mandates  of 
the  Illinois  Groundwater  Protection  Act  for 
ENR  to  carry  out  basic  and  applied  ground- 
water research,  scientists  from  the  ISGS 
and  the  Illinois  State  Water  Survey  (ISWS), 
in  cooperation  with  the  IDOA,  are  conduct- 
ing a  pilot  study  to  evaluate  the  impact  of 
pesticides  and  nitrates  on  groundwater  in 
five  representative  hydrogeologic  settings 
in  the  state.  While  providing  a  preliminary 
estimate  of  the  occurrence  of  agricultural 
chemicals  in  rural  private  water  supplies, 
the  pilot  program  is  helping  evaluate  com- 
ponents of  a  recommended  statewide  sur- 
vey for  agricultural  chemicals  in  rural  wells. 

Besides  evaluating  analytical  methods, 
the  study  has  tested  procedures  to  inven- 
tory sites  of  wells,  conduct  interviews  with 


users  of  the  wells,  and  collect  water  sam- 
ples. Sampling  of  48  randomly-selected 
rural  water  wells  was  completed  in  Febru- 
ary 1 991 .  Analysis  of  240  water  samples 
taken  from  these  wells  for  39  agricultural 
chemicals  extensively  used  in  Illinois  (par- 
ticularly pesticides  with  a  high  potential  to 
move  through  the  soil),  nitrate,  and  nitrite 
were  completed  during  the  year.  Using  the 
USEPA's  methods  employed  in  the  Nation- 
al Pesticide  Survey,  the  ISGS  determined 
20  of  the  compounds,  while  the  ISWS  and 
Department  of  Agriculture  analyzed  other 
compounds.  Reports  describing  the  char- 
acterization process  and  the  overall  project 
are  in  preparation  for  the  funding  agen- 
cies—the Illinois  EPA  (IEPA)  and  ENR. 

This  project  will  establish  base  line  data 
for  pesticides  in  groundwater  in  several 
hydrogeologic  settings  and  will  help  evalu- 
ate criteria  for  predicting  the  potential  for 
contamination  of  rural  wells.  If  scientists 
can  more  accurately  estimate  the  occur- 
rence of  agricultural  chemicals  in  wells  in 
various  hydrogeologic  settings,  they  may 
be  able  to  develop  a  tailored  sampling  pro- 
gram that  can  better  characterize  and  fore- 
cast potential  problem  areas  as  well  as 
result  in  a  more  cost-efficient  sampling  ef- 
fort statewide.  From  these  results,  other 
agencies  could  target  educational  and 
monitoring  programs  for  groundwater  to 
areas  of  greatest  need.... 

Base  line  studies 

In  a  separate  study,  in  accordance  with 
mandates  of  the  Illinois  Groundwater  Pro- 
tection Act  and  in  response  to  the  public's 
concern  over  potential  contamination  of 
groundwater  by  agricultural  chemicals,  the 
IDOA,  the  state's  lead  agency  for  pesticide 
regulation,  initiated  a  survey  to  provide 
statistically  reliable  estimates  of  the  occur- 
rence of  agricultural  chemicals  in  rural, 
private  water  wells  in  the  state.  Of  the  es- 
timated 440,000  private  water  wells  in  Illi- 
nois, approximately  360,000  are  in  rural 
areas. 

The  Geological  Survey  is  cooperating 
with  the  Department  of  Agriculture  and  the 
Cooperative  Extension  Service  of  the 
University  of  Illinois  at  Urbana-Champaign 
in  this  statewide  project  in  which  ground- 
water samples  are  being  collected  from  ap- 
proximately 340  randomly-selected  wells 
and  analyzed  for  nitrate,  nitrite,  a  number 
of  pesticides  and  metabolites.  Sampling 
began  in  March  1991. 

Primarily  responsible  for  development  of 
the  sampling  plan  and  procedures  for  col- 
lecting samples,  the  ISGS  is  also  providing 


Ivan  Krapac,  geochemist,  spikes  a  field  sam- 
ple of  groundwater  with  a  known  concentra- 
tion of  a  pesticide  for  which  analyses  will  be 
made  in  the  laboratory.  These  spiked  sam- 
ples check  on  the  accuracy  of  lab  analyses. 

geologic  characterization  of  the  areas  in 
which  samples  are  being  collected  and  will 
assist  in  interpreting  the  final  results.  Rela- 
tionships among  the  quality  of  well  water, 
use  of  agricultural  chemicals,  and  the  vul- 
nerability of  an  aquifer  will  be  investigated 
in  the  statistical  analysis  of  results  from  this 
survey. 

Because  no  complete  list  exists  of  the 
rural,  private  water  wells  in  the  state,  scien- 
tists used  a  two-stage  probability  sampling 
plan.  In  stage  one,  they  randomly  selected 
200  land  sections  and  developed  a  com- 
plete list  of  all  dwellings  and  private  wells 
within  the  rural  area  of  each  section.  In 
stage  two,  staff  members  randomly  select- 
ed approximately  340  private  water  wells 
from  the  list  of  wells  in  the  rural  area  of 
each  section  containing  such  wells,  ac- 
quired permission  to  sample  wells,  and 
conducted  interviews  with  the  users  of  the 
wells. 

Researchers  are  collecting  samples 
over  a  13-month  period,  scheduled  to 
spread  collections  across  all  seasons  and 
periods  for  applications  of  pesticides  and 
fertilizers.  In  addition  to  data  they  acquired 
from  the  well-user  interview  and  well-site- 
characterization  form,  they  are  compiling 
soil  and  geologic  data  for  each  site. 

Results  of  this  statewide  survey  will  pro- 
vide the  first  statistically  reliable  estimates 
of  the  extent  of  contamination  caused  by 


agricultural  chemicals  in  rural,  private  water 
wells  in  Illinois.  The  survey  should  also  pro- 
vide some  information  on  the  factors  affect- 
ing contamination  of  private  wells.  By 
identifying  areas  where  private  wells  are 
more  vulnerable  to  contamination  and  by 
identifying  pesticides  that  are  more  likely  to 
cause  contamination,  the  study  may  pro- 
vide a  basis  for  more  accurate  targeting  of 
future  monitoring  programs  in  the  state.... 

In  yet  another  project  with  the  IDOA,  the 
Geological  Survey  is  assisting  in  address- 
ing the  1990  amendments  to  the  Illinois 
Pesticide  Act  which  require  the  Department 
of  Agriculture  to  develop  guidelines  and 
recommendations,  including  long-term 
financial  expenditures  which  may  be  neces- 
sary to  remediate  contamination  caused  by 
pesticides. 

Through  this  reporting  period,  the  ISGS 
has  completed  a  review  of  alternative  sam- 
pling plans  for  selecting  specific  agrichemi- 
cal  facilities  for  on-site  assessments.  Sci- 
entists have  performed  an  initial  screening 
of  the  potential  for  aquifer  contamination  at 
50  randomly-selected  facilities,  based  on 
existing  geologic  mapping  at  a  scale  of 
1:250,000.  In  addition,  the  Geological  Sur- 
vey has  provided  assistance  in  developing 
technical  standards  for  conducting  phase  1 
and  2  environmental  site  assessments  at 
20  agrichemical  facilities.  The  actual  eval- 
uation and  assessment  of  conditions  and 
operational  practices  at  these  facilities  will 
be  conducted  by  other  contractors.... 


Studies  on  fate  of  atrazine 

Subsurface  movement  of  atrazine,  a  her- 
bicide, and  de-ethylatrazine  and  deisopro- 
pylatrazine,  primary  degradation  products 
of  atrazine,  are  being  studied  to  estimate 
the  relative  contribution  of  surface-water 
runoff  and  shallow  groundwater  discharge 
to  pesticide  loadings  in  streams.  A  small 
watershed  in  east-central  Illinois  is  the  focal 
point  of  this  study. 

Atrazine  and  its  degradation  products 
were  present  in  water  samples  from  the 
stream  throughout  most  of  the  year.  Con- 
centrations of  atrazine  in  individual  water 
samples  ranged  from  4.9  micrograms  per 
liter  in  late  May  to  less  than  1 .0  microgram 
per  liter  during  June.  The  average  con- 
centration of  atrazine  in  samples  exceeded 
one  microgram  per  liter  in  the  five  sampling 
periods  from  April  17  to  May  29,  1991 ,  ex- 
cept for  samples  collected  on  May  1 . 
Atrazine  was  applied  to  cropland  in  the 
watershed  from  late  April  through  early 
May.  This  high  concentration  of  atrazine 
coincided  with  increased  surface-water 
runoff  and  stream  discharge  in  response  to 
more  than  nine  inches  of  rainfall  during  the 
month.  The  occurrence  of  these  com- 
pounds in  water  samples  from  the  stream 
during  the  remainder  of  the  year  may  be 
the  result  of  the  discharge  of  groundwater 
into  the  stream,  discharge  of  tile-drainage 
water,  or  desorption  (detachment)  of  atra- 
zine from  stream-bed  sediments. 


15 


A  mobile  drill  rig  was 
used  to  install  eight 
13-foot-deep  nests, 
six  nests  in  the  field 
and  two  in  the  stream. 
The  six  field  nests  in- 
cluded a  water-table 
monitoring  well  and 
three  piezometers 
(one  to  measure 
depth  of  water  table 
and  the  other  two  to 
measure  water  pres- 
sure within  the  till  and 
the  sand). 


16 


The  adsorption  (attachment)  of  atrazine 
by  surface  soils  is  well  understood,  but  few 
studies  exist  on  the  movement  of  atrazine 
in  deeper  materials  containing  low  levels  of 
organic  carbon.  Research  indicates  that 
this  pesticide's  adsorption  by  such  materi- 
als may  be  under  estimated.  Laboratory 
measurements  disclosed  that  the  extent  of 
atrazine  adsorption  may  be  one  to  five 
times  greater  than  predicted  by  the  organic- 
carbon  content,  an  observation  consistent 
with  other  studies. 


A  continuous  soil  core  was  collected  to  a 
depth  of  four  meters  at  each  nest  site  when 
the  wells  and  piezometers  were  installed. 
Samples  from  these  cores  will  be  used  for 
adsorption  studies  of  atrazine. 

Measurements  have  indicated  that 
atrazine  does  not  desorb  (detach)  readily 
during  short-term  intervals.  As  the  organic- 
carbon  content  increases,  the  degree  of 
irreversibility  also  increases.  This  lack  of 
reversibility  may  be  the  result  of  slow  de- 
sorption  or  a  reaction  of  atrazine  with  the 
organic  matter  to  form  chemical  bonds. 
However,  once  below  the  surface  soil, 
atrazine's  subsequent  migration  will  be 
slightly  retarded  by  adsorptive-desorptive 
interactions,  depending  on  the  distribution 
of  organic  matter  in  the  subsurface  and  the 
acidity  or  alkalinity  of  the  groundwater. 
Studies  with  de-ethylatrazine  will  begin 
next  fiscal  year.  This  research  is  being 
funded  by  the  U.S.  Department  of  Agricul- 
ture's Cooperative  State  Research  Service 
through  the  Groundwater  Research  Con- 
sortium of  Southern  Illinois  University  at 
Carbondale.... 

And  more 

Researchers  also  evaluated  the  utility  of 
monitoring  drainage-tile  effluent  for  pes- 
ticides as  a  potential  alternative  to  the  in- 
stallation and  monitoring  of  large  networks 


of  groundwater-monitoring  wells.  They  col- 
lected samples  from  drainage  tiles,  soil- 
water  samplers,  monitoring  wells  and  soil. 
Results  demonstrate  that  pesticide  con- 
centrations in  drainage-tile  effluent  can  be 
used  to  evaluate  the  leaching  behavior  of 
these  compounds  in  the  field,  provided  cer- 
tain information  is  known  regarding  the 
layout  of  the  tile  system  and  the  local 
hydrogeologic  setting.... 

To  clarify  potential  problems  of  regional 
contamination  caused  by  agricultural  chemi- 
cals, the  USEPA  Region  V  also  supported 
the  production  of  a  Contamination  Potential 
Map  of  the  Chicago  Sheet,  covering  parts 
of  Illinois,  Indiana,  Ohio,  Michigan  and  Wis- 
consin. This  map  was  produced  in  a 
cooperative  effort  by  the  USGS  and  the 
ISGS,  using  the  USGS'  texturally-based, 
three-dimensional  maps.  Currently,  the 
USGS  is  statistically  evaluating  the  validity 
of  information  portrayed,  comparing  con- 
tamination potential  units  on  the  map  to  ac- 
tual contamination  of  wells  by  nitrates. 

Again  responding  to  the  Groundwater 
Protection  Act,  the  Survey  has  generated  a 
map,  "Potential  for  Aquifer  Recharge  in  Illi- 
nois," which  shows  recharge  areas  based 
on  depth  to  aquifers  and  surface-soil  infiltra- 
tion. It  can  also  be  used  to  evaluate  the 
potential  for  contamination  of  aquifers.... 

The  ISGS  and  the  ISWS,  in  cooperation 
with  the  IEPA,  are  using  the  new  recharge 
map  and  a  number  of  other  geologic  maps 
in  a  detailed  pilot  study  of  the  geologic  and 
hydrologic  aspects  of  the  Woodstock  area. 
The  study  will  establish  methodology  for 
making  groundwater  protection  needs  as- 
sessments to  be  used  in  assisting  local 
governments  with  evaluating  aquifer  char- 
acteristics and  defining  areas  of  potential 
contamination. 

Thus  far,  scientists  at  the  Surveys  have 
compiled  preliminary  versions  of  cross  sec- 
tions, isopach  maps  of  four  aquifers  that 
were  discovered  in  the  area,  a  stack-unit 
map  of  materials  to  a  depth  of  1 00  feet, 
and  a  map  depicting  the  potential  for  con- 
tamination of  aquifer  materials  for  the 
Woodstock  7.5-minute  topographic  Quad- 
rangle. They  are  also  statistically  analyzing 
the  chemical  data  and  drafting  reports. 

Pressure  is  mounting  for  more  detailed 
geologic  mapping  statewide.  Such  maps 
are  being  used  as  tools  to  investigate  and 
solve  environmental  problems,  aid  in  re- 
source management,  and  help  prioritize 
geographic  areas  most  in  need  of  evalu- 
ation, monitoring,  or  perhaps  remedial 
technology. 


Geologic  Mapping  Provides 
Problem-Solving  Information 


Because  the  Earth's  materials  are  essential 
to  modern  life  and  their  consumption  can 
cause  environmental  problems,  mankind 
needs  to  understand  their  nature  and  dis- 
tribution. After  all,  the  populace  lives  and 
depends  on  these  materials,  extracting 
water  and  minerals  from  them;  depositing 
waste  in  them;  constructing  roads,  dams, 
and  buildings  from  and  on  them;  and  is  af- 
fected by  hazards,  like  earthquakes,  land- 
slides and  subsidence,  involving  them. 
Geologic  maps  provide  information 
which  mankind  can  use  to  help  solve  its 
many  earthbound  environmental  and 
resource-related  problems.  Such  maps 


Looking  over  a  sand  isolith  map  of  Lake  County  to  be  used  to  help 
site  a  landfill  are  Don  McKay,  senior  geologist  and  head  of  the  Geo- 
logical Mapping  and  Digital  Cartography  Section,  Lisa  Smith  and 
Bob  Pool,  geologists.   The  map  was  prepared  using  GIS  software. 

illustrate  the  character  of  materials  at  or 
below  the  ground's  surface,  depicting  soils 
of  various  types,  sand  or  sandstones,  silts 
or  siltstones,  clays  or  shales,  limestones  or 
dolomites,  varieties  of  glacial  deposits, 


coals  and  other  mineral  resources,  their 
ages,  physical  character,  and  lateral  and 
vertical  distribution. 

How  much  information  can  be  presented 
on  a  geologic  map?  A  map's  scale  deter- 
mines the  detail  shown.  The  geology  of  the 
entire  state  on  one  sheet  of  paper,  even  if  it 
is  a  large  wall  map,  does  not  permit  much 
detail.  On  the  1 :500,000-scale  geologic 
map  of  Illinois,  for  example,  one  inch  repre- 
sents about  eight  miles  on  the  ground;  1/32 
inch,  about  the  thickness  of  a  heavy  line, 
equals  1 ,320  feet  on  the  ground.  Maps 
that  permit  representation  of  greater  detail 
are  the  1 :24,000-scale  7.5-minute  topo- 
graphic quadrangles.  On  these  maps,  one 
inch  represents  2,000  feet  on  the  ground, 
permitting  about  20  times  the  resolution  of 
statewide  1 :500,000-scale  maps.  Although 
a  line  1/32-inch  wide  on  the  1 :24,000-scale 
map  still  represents  about  62  feet  on  the 
ground,  this  scale  allows  city  blocks  to  be 
shown  without  difficulty. 

While  regional  geologic  map  coverage 
of  Illinois  is  available  at  scales  from 
1 :500,000  to  1 :250,000,  a  lack  of  funding 
has  prevented  the  development  of  state- 
wide geologic  maps  at  scales  detailed 
enough  (1:24,000  to  1:100,000— one  inch 
equalling  1.6  miles)  for  today's  planning 
and  decision-making  purposes,  focusing  on 
rapidly  increasing  environmental  concerns 
and  continuing  pressures  for  and  from 
economic  development. 

Such  highly  detailed  geologic  maps 
often  are  required  for  decision  making  by  in- 
dustry in  locating  resources,  siting  facilities, 
and  undertaking  construction  projects. 
Municipal,  county,  state,  and  federal 
governmental  agencies  need  the  same 
kinds  of  maps  for  planning  purposes  and 
assessing  competing  land  uses;  selecting 
areas  where  geologically  appropriate  sites 


17 


18 


for  landfills  and  even  nuclear  waste  dis- 
posal facilities  are  likely  to  occur;  selecting 
areas  where  facilities  such  as  hospitals  or 
schools  can  be  safely  located;  developing 
zoning  regulations;  and  assessing  the 
value  of  land.  Private,  public  and  govern- 
mental sectors  need  these  highly  detailed 
geologic  maps  for  the  development  and 
protection  of  groundwater  resources  and  to 
identify  hazards  and  assess  the  potential 
damage  from  earthquakes,  landslides,  sub- 
sidence and  coastal  erosion. 

The  principal  source  of  geologic  maps 
for  Illinois  is  the  ISGS  by  virtue  of  man- 
dates of  the  General  Assembly  and  the 
Survey's  tradition  of  investigating  and 
reporting  on  the  geology  of  Illinois.  While 
statewide  maps  exist  on  regional  scales, 
only  three  percent  of  the  state  is  covered 
by  published  maps  at  the  detailed  1 :24,000 
scale  required  for  many  current  applica- 
tions. The  only  sizeable  areas  with  ade- 
quate coverage  at  that  scale  are  the  Illinois 
Kentucky  Fluorspar  District  of  southeastern 
Illinois,  the  adjacent  coal-field  area  in 
southern  Illinois,  and  the  Chicago  area  of 
northeastern  Illinois.  These  maps  are  ac- 
companied by  detailed  geologic  reports. 
The  Chicago-area  maps  were  published  in 
the  1940s;  the  Fluorspar  District  maps,  in 
the  1 960s;  and  maps  of  the  coal-field  area, 
in  the  1 980s  and  1 990s. 

Mapping  area,  rich  in  resources 

The  latter  maps  are  part  of  an  ongoing 
geologic  mapping  program  that  has  been 


supported  since  1984  by  the  USGS  and  the 
State  of  Illinois  under  the  Cooperative  Geo- 
logic Mapping  Program  (COGEOMAP). 
This  region  of  southern  Illinois,  while  rich  in 
some  areas  in  such  mineral  resources  as 
coal,  oil,  gas  and  fluorspar,  is  underdevel- 
oped. The  geology  of  the  southernmost 
portion  of  the  region  is  more  complex  than 
other  parts  of  the  state,  and  its  details  are 
only  now  beginning  to  be  understood. 

Through  COGEOMAP,  renewed  efforts 
by  the  Survey's  mappers  have  located  new 
seams  of  coal.  However,  these  are  gener- 
ally thinner  and  less  easily  mined  than 
other  coals  in  the  state,  and  their  sulfur  con- 
tent is  not  as  low  as  expected.  Detailed 
mapping  also  is  changing  geologic  con- 
cepts of  the  region  in  ways  that  could  pro- 
vide new  tools  for  successful  exploration  of 
oil  and  gas.  Faults  outside  the  Illinois  Fluor- 
spar Mining  District  have  been  mapped  in 
detail  and  are  potential  targets  for  mineral 
exploration. 

The  original  COGEOMAP  program  calls 
for  the  publication  of  16  7.5-minute  geo- 
logic quadrangles;  six  of  these  have  been 
published  and  three  are  currently  in  produc- 
tion. Another  four  quadrangles  in  south- 
western Illinois  were  added  this  year  for 
mapping  by  1993. 

Further  expansion  of  the  COGEOMAP 
program  in  Illinois  during  this  reporting  per- 
iod brings  the  mapping  effort  into  the  east- 
central  part  of  the  state.  The  USGS  has 
awarded  the  Survey  a  contract  to  develop 
an  advanced  methodology  for  three-dimen- 


While  in  the  field 
working  on  the 
Cooperative  Geo- 
logic Mapping 
Project  (COGEO- 
MAP), a  scientist 
climbs  a  lime- 
stone outcrop 
along  the  Missis- 
sippi River  in  the 
Grand  Tower 
area. 


sional  mapping  of  Quaternary  (glacial)  de- 
posits in  the  Champaign  1:100,000-scale, 
1/2-by-1  -degree  Quadrangle. 

Through  the  Conterminous  U.S.  Mineral 
Assessment  Program  (CUSMAP),  a  coop- 
erative project  among  the  USGS  and  the 
State  Geological  Surveys  of  Illinois,  In- 
diana, Kentucky  and  Missouri,  geologic  in- 
formation is  being  summarized  on  maps  at 
the  1 :250,000  scale  (one  inch  equals  ap- 
proximately four  miles)  from  an  original 
compilation  at  a  1 :1 00,000  scale  for  a 
5,000-square-mile-area  of  Illinois  south  of 
Benton  and  DuQuoin.  This  project  pro- 
vides detailed  geological,  geochemical  and 
geophysical  (seismic,  gravity  and  magnet- 


Barb  Stiff,  GIS  specialist,  Mike  Sargent,  seated,  geologist  in  the 
Basin  and  Crustal  Analysis  Section,  and  Jim  Baxter,  senior  geologist 
and  head  of  the  Industrial  Minerals  and  Metals  Section,  examine  a 
map  showing  potential  veins  of  fluorspar  in  Illinois.  Assessment 
maps  for  about  20  commodities  and  many  intermediate  maps  were 
produced  digitally  for  a  Paducah  CUSMAP  meeting. 

ic)  studies  in  regions  known  to  contain  or 
have  potential  for  mineral  deposits  such  as 
fluorspar,  lead,  zinc  and  industrial  minerals 
(sand,  gravel,  limestone)  and  others.  Its 
goal  is  to  develop  sufficient  knowledge  to 
determine  the  likelihood  of  finding  new 
mineral  resources  or  extensions  of  known 
deposits  in  the  Paducah  1  -by-2-degree 
Quadrangle,  covering  approximately  7,500 
square  miles  in  the  states  involved. 

The  ISGS  has  coordinated  much  of  this 
research  effort  and  data  input  and,  with  the 
USGS,  has  taken  the  lead  in  developing  a 
computer  data  base  for  the  ISGS'  Geo- 
graphic Information  System  (GIS)  that  incor- 
porates new  techniques  in  computer- 
assisted  spatial  data  analysis  and  cartog- 
raphy for  the  Paducah  CUSMAP  project. 
Scientists  have  completed  research  and  ac- 
quisition of  data  and,  using  the  GIS,  have 
prepared  maps  showing  areas  of  high, 


moderate,  and  low  potential  for  mineral  dis- 
covery. They  will  release  results  of  the 
resource  assessment  at  a  public  meeting  in 
January  1992. 

GIS  integrates,  synthesizes  data 

The  efficacy  of  the  computer  technology  for 
assessing  mineral  potential  was  demon- 
strated in  April  1991  at  a  workshop  held  in 
Champaign.  As  the  name  GIS  implies,  the 
geographic  or  spatial  nature  of  information 
is  fundamental.  Geographic  location  of 
natural  and  cultural  features  provides  a 
framework  in  which  diverse  data  can  be 
compiled  and  integrated  to  discover  rela- 
tionships and  generate  new  information. 
The  GIS'  functions  of  integration  and  anal- 
ysis provide  a  mechanism  for  combining  in- 
formation, testing  multiple  scenarios,  and 
presenting  the  results  in  map  form  that  is 
easy  to  understand.  Thus,  the  GIS  can  be 
an  invaluable  tool  for  integrating  and  syn- 
thesizing information  required  to  make  criti- 
cal choices  and  solve  problems  that  face 
Illinois. 

In  using  the  GIS  as  a  tool  to  assess  re- 
source potential  for  CUSMAP,  geologists  in- 
itially wanted  to  translate  all  available  data 
into  a  digital  format  and  use  the  GIS  to  cal- 
culate the  relative  potential  for  each  type  of 
mineral  deposit.  Thus,  they  developed  tech- 
niques for  digitizing  maps  and  translating 
numerous  types  of  data  into  the  GIS  format. 

To  produce  a  map  depicting  an  area  of 
relative  mineral  potential,  the  scientists 
created  a  digital  model  of  deposits  for  each 
mineral,  using  descriptive  deposit  models 
that  defined  diagnostic  criteria  and  quan- 
tified numerous  criteria  describing  ore 
deposits.  For  example,  permissive,  neces- 
sary and  critical  criteria  were  specified  in 
many  of  the  descriptive  models.  While 
creating  quantified  digital  models  from  the 
descriptive  models,  staff  members  needed 
a  numeric  weighting  scheme  to  reflect  the 
relative  importance  of  each  criterion.  This 
process  involved  selecting  the  most  impor- 
tant diagnostic  criterion  necessary  for  the 
occurrence  of  the  mineral  deposit  being 
considered  and  assigning  its  presence  an 
arbitrary  high-value  weight.  Other  criteria 
were  assigned  lesser  weights  relative  to 
their  individual  importance  in  the  model. 
Weighted  criteria  were  then  combined. 

When  all  of  the  layers  of  a  deposit 
model  were  combined  using  the  GIS  over- 
lay technique,  areas  of  relative  resource 
potential  were  drawn.  Based  on  the  total 
model  weight  assigned  to  each  area, 
those  with  higher  and  lower  potential  for 
mineral  occurrence  could  be  identified. 


19 


The  purpose  of  these  maps  is  to  highlight 
areas  which  might  have  mineral  resour- 
ces— areas  which  could  be  targets  for  fu- 
ture research  and  exploration. 

Upon  completion  of  the  project,  the 
ISGS  with  the  USGS  will  publish  a  series  of 
reports  on  the  geology  and  mineral  resour- 
ces of  the  Paducah  Quadrangle.  These 
will  include  new  and  innovative  compila- 
tions of  resource  data  related  to  coal,  oil, 
gas,  and  the  industrial  mineral  and  metal 
resources;  detailed  surficial,  bedrock  and 
subsurface  maps  and  cross  sections;  topi- 
cal studies;  and  a  general  assessment  of 
the  mineral  potential  of  the  area.  Avail- 
ability of  this  information  coupled  with  the 


20 


Bob  Pool,  GIS  geologist,  views  a  model  created  for  the 
CUSMAP  study. 

development  of  new  theories  and  models 
could  make  southern  Illinois  more  attractive 
for  mineral  exploration  and  entrepreneurial 
activity. 

Rock  units,  structures  identified 

Besides  showing  topographic  elevations 
and  geographic  features,  a  detailed  geo- 
logic map  uses  various  colors  and  symbols 
to  show  the  relationships  of  rock  units  that 
are  exposed  at  the  surface.  One  such 
map,  the  Equality  Quadrangle,  covering  an 
area  in  Gallatin  County  near  the  village  of 
Equality,  also  shows  the  location  of  major 
coal  seams  and  where  the  coals  have  been 
mined  out.  By  knowing  the  lateral  extent 
and  thickness  of  the  coals  and  what's  been 
mined,  one  can  estimate  the  quantity  of 
coal  remaining.  This  detailed  map  also 
identifies  structures  such  as  faults.  In  near- 
by areas,  faults  have  trapped  oil  or  have 
contributed  to  the  formation  of  other  min- 
eral resources  such  as  fluorspar.  Thus, 
these  maps  convey  information  useful  in 
assessing  the  potential  for  discoveries  of  oil 
and  gas  and  other  mineral  resources.  They 
also  provide  basic  information  and  ideas 


seful  to  industry  in  exploring  and  develop- 
ing the  state's  resources. 

Detailed  geologic  maps  can  be  especial- 
ly helpful  in  resolving  issues  related  to  the 
environment,  for  example,  in  protecting 
groundwater  resources  from  contamination. 
A  map  of  Boone  and  Winnebago  counties, 
originally  compiled  at  the  scale  of  one  inch 
equals  2,000  feet,  was  printed  at  the  more 
reduced  scale  of  1 :62,500— one  inch 
equals  about  a  mile.  This  particular  map 
was  derived  from  the  detailed  geological 
map,  called  a  stack-unit  map,  which  shows 
the  nature  of  earth  materials  down  to  a 
depth  of  20  feet.  The  derivative  map 
depicts  areas  more  susceptible  to  the  con- 
tamination of  groundwater.  In  particular, 
sands  and  gravels  and  the  fractured 
bedrock  (a  significant  aquifer  in  the  area) 
occurring  within  20  feet  of  the  surface  are 
differentiated  from  areas  less  susceptible — 
the  more  impermeable  glacial  materials 
(tills)  that  are  more  favorable  for  landfills. 
These  tills  act  as  barriers  to  contamination 
of  groundwater  resources. 

Unfortunately,  before  the  need  for  this 
type  of  information  became  known  and 
before  these  maps  could  be  developed  for 
Boone  and  Winnebago  counties,  numerous 
landfills  had  already  been  located  in  the 
areas  most  susceptible  to  the  contamina- 
tion of  groundwater.  Leakage  from  existing 
landfills  into  groundwater  was  virtually  as- 
sured. To  date,  some  four  Superfund 
Sites,  subject  to  clean  up,  have  been  iden- 
tified in  Winnebago  County.  Cleaning  up 
those  sites  will  be  very  costly.  (Published 
figures  indicate  that  the  average  cost  of 
cleaning  up  a  Superfund  Site  is  between 
$20  million  and  $30  million.)  If  these  kinds 
of  geologic  maps  had  been  available  when 
applications  for  these  disposal  sites  were 
being  considered,  the  need  for  and  cost  of 
clean  up  might  have  been  avoided.  Landfill 
applicants  and  public  officials  would  have 
known  the  more  geologically  favorable 
areas  and  could  have  located  the  landfills 
accordingly.  The  cost  of  the  project  to 
develop  this  map  for  the  two  counties  was 
approximately  $250,000 — an  investment, 
which,  if  made  even  earlier,  could  have 
helped  avoid  future  multi-million-dollar- 
clean-up  costs  at  the  Superfund  Sites, 
giving  some  appreciation  of  the  pay  back 
possible  from  this  type  of  detailed  geologi- 
cal mapping. 

Benefits,  costs  analyzed 

In  a  definitive  study  for  Boone  and  Winne- 
bago counties,  the  Survey  quantified  the 
benefits  of  detailed  geologic  mapping. 


Staff  members  compared  the  benefits  to 
the  cost  of  mapping  discussed  above.  The 
return  on  an  investment  of  $300,000  in 
1990  dollars  was  about  23  to  54  times  the 
investment  for  the  best-case  scenario  and 
5  to  1 1  times  the  investment  for  the  worst- 
case  scenario.  The  most  probable  case  in- 
dicated benefit/cost  ratios  of  1 1 .7  to  27.2. 
Benefits  were  calculated  from  avoided 
costs  associated  with  the  clean  up  of  land- 
fills and  industrial  disposal  sites.  The  bene- 
fit/cost analysis  excluded  other  benefits 
that  are  not  currently  quantifiable  such  as 
identifying  and  recovering  the  Earth's 
resources  and  providing  basic  data  to  in- 
dustry and  government  for  siting  facilities — 
data  indicating  water  supplies,  foundation 
conditions,  and  areas  suitable  for  the  instal- 
lation of  septic  tanks.  Such  benefits  would 
increase  the  benefit/cost  ratios  significantly, 
just  as  they  have  in  Kentucky. 

Over  an  18-year  period  in  the  1960s  and 
1970s,  Kentucky  was  mapped  at  this  de- 
tailed scale  at  a  cost  of  $21  million.  Since 
then,  the  maps  have  been  used  extensive- 
ly. The  Kentucky  Geological  Survey  esti- 
mates that  the  cost  of  the  mapping  has 
been  repaid  to  the  state  at  least  50  times 
over,  coming  from  new  coal  mines  opened 
in  areas  where  new  coal  resources  were 
mapped  and  from  new  oil  and  gas  wells 
drilled  into  oil  and  gas  reservoirs  near  faults 
that  had  previously  been  unknown.  In  addi- 
tion, the  pay  back  has  come  from  savings 
derived  from  locating  new  highways  that 
avoided  landslide-prone  areas.  The  maps 
also  found  widespread  use  in  siting  farm 
ponds  and  industrial  facilities  in  Kentucky. 


County  officials  listen  to  Rob  Krumm,  center,  geologist,  and  Curtis 
Abert,  assistant,  seated,  of  the  Geologic  Mapping  and  Digital  Cartog- 
raphy Section,  who  are  explaining  computer  mapping  used  for  regional 
screening  to  determine  areas  geologically  capable  of  being  landfill  sites. 


The  ISGS  prepared  a  report,  "Geologic 
Mapping  for  the  Future  of  Illinois,"  for  the  Il- 
linois Senate  Committee  on  Geologic  Map- 
ping and  presented  it  in  July  1 991 .  This 
report  included  a  detailed  analysis  of  geo- 
logic mapping  needs  and  prioritized  the 
mapping  of  the  1 ,073  7.5-minute  quad- 
rangles in  the  state.  Based  on  prioritized 
needs  and  uses,  detailed  geologic  maps 
are  required  in  Illinois  to: 

•  ensure  sufficient  present  and  future 
supplies  of  groundwater; 

•  protect  groundwater  in  areas  of  high 
usage  and  help  assess  the  impact  of 
agricultural  chemicals  on  the  quality 
of  groundwater; 

•  plan  landfill  sites  in  the  most  popu- 
lated counties  or  rapidly  developing 
corridors  with  high  priority  given  where 
capacity  is  most  limited  and  where 
county  plans  indicate  imminent  need 
for  a  suitable  site; 

•  assess  geologic  and  related  hazards, 
especially  seismic  risk  and  threat  of 
landslides,  coastal  erosion  and  sub- 
sidence; 

•  select  sites  for  development,  especial- 
ly in  areas  of  rapid  growth; 

•  permit  comprehensive  assessment  of 
strategic  and  critical  minerals; 

•  identify  location  and  extent  of  deposits 
of  sand,  gravel,  limestone,  dolomite 
and  other  industrial  minerals  for  the 
entire  state,  giving  highest  priority  to 
metropolitan  areas  where  construction 
needs  are  greatest; 

•  locate  deposits  of  low-  to  moderate- 
sulfur  coal; 

•  determine  the  nature  and  structure  of 
bedrock,  useful,  for  example,  in  the  ex- 
ploration for  and  development  of  oil 
and  gas; 

•  introduce  the  public  to  Earth  Science 
in  parks,  national  corridors  and  other 
recreational  areas. 

Such  maps  are  required  to  aid  in 
economic  development,  environmental 
protection  and  risk  assessment.  The 
recommended  geologic  mapping  program, 
designed  to  meet  these  expressed  needs 
in  priority  order,  is  a  long-term,  multi-year 
effort,  requiring  dedicated  funds.  The 
recommended  level  of  state  funding  for  this 
program  is  $1.1  million  per  year  over  a 
period  of  50  years. 


21 


Mapping,  very  restricted 

Currently,  the  geologic  mapping  effort 
operated  by  the  ISGS  under  the  General 
Revenue  Funds  includes  a  staff  of  2.9  full- 
time  staff  equivalents  with  an  annual  expen- 
diture of  approximately  $170,000.  During 
the  decade  of  1982-1991,  the  ISGS  will 
have  mapped  43  7.5-minute  quadrangles 
and  published  them  at  a  scale  of  one  inch 
equals  one  mile  or  more  detailed  under  the 
COGEOMAP  and  pollution  prevention 
programs.  Included  are  about  16  quad- 
rangles in  Boone  and  Winnebago  counties, 
about  18  in  Champaign  County,  and  nine  in 
the  coal-field  area  of  southern  Illinois.  The 


22 


Geologist  Joe  Devera  examines  a  fossilized  log  in  a  bedrock  out- 
crop in  southern  Illinois. 

total  effort  is  small  and  restricted  geographi- 
cally and  functionally.  At  this  rate,  more 
than  200  years  would  be  required  to  com- 
pletely map  Illinois  at  a  detailed  scale.  The 
pressures  of  environmental  and  economic 
concerns  will  not  permit  such  a  slow  time- 
table in  Illinois. 

Similar  needs  exist  in  every  other  state 
except  Kentucky  and  possibly  Massachu- 
setts, Rhode  Island  and  Puerto  Rico,  which 
have  been  mapped  at  the  suggested  de- 
tailed scales.  Mapping  Kentucky  and  the 
other  states  was  aided  by  the  availability  of 
detailed  topographic  maps  at  a  scale  of 
one  inch  equaling  2,000  feet.  These  maps 
are  now  available  for  all  of  the  lower  48 
states,  thus  making  more  detailed  geologic 
mapping  feasible. 

Obviously,  a  state  and  federal  program 
of  geological  mapping  is  needed.  Pay  back 


may  be  expected  on  the  basis  of  saving 
clean-up  costs  of  disposal  sites  alone. 
Other  benefits  will  accrue  in  the  delineation 
of  mineral  resources  that  will  aid  in  building 
and  rebuilding  the  nation's  infrastructure;  in 
the  delineation  of  groundwater  resources 
and  their  potential  for  contamination;  and  in 
the  delineation  of  geologic  hazards  and 
their  risk  to  public  health,  safety  and  proper- 
ty. Proposed  legislation,  if  enacted,  will  pro- 
vide the  basis  for  a  sound  investment  in  the 
future  of  the  nation  and  Illinois. 

Thus,  passage  is  needed  of  the  Geo- 
logic Mapping  Act  of  1991 ,  a  bill  that  has 
been  introduced  in  Congress  to  facilitate 
the  production  of  the  required  detailed 
maps.  The  key  element  of  the  proposed 
program  is  the  State  Geologic  Mapping 
Component,  calling  for  matched  state  and 
federal  funds,  starting  at  $15  million  and 
stepping  up  to  $25  million  per  year  in  the 
fourth  year.  A  multi-year  effort,  the  pro- 
gram requires  secure,  dedicated  funds. 
The  House  passed  its  version  of  the  bill  in 
late  1991.  The  Senate  and  Congress  are 
expected  to  pass  the  legislation  in  the  cur- 
rent session.  Support  of  the  appropriation 
is  needed  to  implement  the  authorizing 
legislation. 

Parallel  legislation  at  the  state  level  is  re- 
quired to  ensure  proper  coordination  of  the 
state  and  federal  programs  and  to  imple- 
ment a  prudent  program  to  meet  Illinois' 
needs  in  a  timely  way.. .to  ensure  that  this 
state  is  in  a  position  to  participate  and  re- 
ceive its  share  of  federal  funds.  A  federal 
appropriation  at  the  $15  million  level  and 
growing  to  $25  million  should  provide  be- 
tween $700,000  to  $1,100,000  per  year  in 
federal  funds  to  Illinois  for  mapping.  The 
addition  of  state  matching  funds  may  per- 
mit Illinois  to  be  mapped  at  a  scale  of  one 
inch  equals  2,000  feet  in  about  25  to  35 
years,  depending  on  the  level  of  funding. 
Thus,  time  can  be  reduced  in  half  with 
federal-state  matching  funds  and  perhaps 
to  17  or  18  years  with  contributions  from 
other  beneficiaries  such  as  local  and  coun- 
ty governments  and  industry  in  Illinois. 

A  state  and  federal  program  of  geologi- 
cal mapping  is  in  the  national  interest. 
Benefit/cost  studies  indicate  that  geologic 
maps  will  save  the  nation  and  state  money. 
The  proposed  legislation,  if  enacted,  will 
provide  the  basis  for  a  sound  investment  in 
the  future  of  the  United  States  and  Illinois. 


Future  Challenges  Abound 


Research  investigations  and  service  efforts 
of  the  ISGS  address  the  state's  issues  or 
anticipated  needs,  taking  trends  into  ac- 
count. Such  trends  include  a  greater  con- 
cern for  the  environment  and  quality  of  life. 
In  fact,  the  Governor's  office  asked  ENR  to 
develop  a  program  to  assess  the  environ- 
ment in  Illinois.  Based  upon  a  report  by  the 
Science  Advisory  Board  of  the  USEPA,  the 
Geological  Survey  and  the  other  scientific 
divisions  of  ENR  evolved  a  plan  to  conduct 
and  report  on  a  critical  trends  assessment 
of  environmental  elements  in  the  state. 

This  Critical  Trends  Assessment  Project 
will  use  the  extensive  data  base  for  Illinois 


From  the  left,  Jimmy  Cooper,  craftsman,  Dave  Moran,  chemical  en- 
gineer, and  Massoud  Rostam-Abadi,  senior  chemical  engineer, 
prepare  to  operate  the  process  optimization  unit  which  will  provide 
engineering  data  for  the  scale-up  of  the  Geological  Survey's  process 
producing  high-surface-area  hydrated  lime.  This  product  will  increase 
the  effectiveness  of  dry-injection  systems  for  decreasing  sulfur-dioxide 
emissions,  producing  results,  in  pilot-scale  tests,  sufficient  to  bring 
Illinois'  coals  into  compliance  with  the  goals  of  acid  rain  legislation  for 
the  year  2001.  A  patent  covering  the  process  has  been  applied  for. 


and  the  computerized  IGIS  to  advance  the 
management  of  the  state's  environment 
and  natural  resources  into  the  next  century. 
Two  goals  are  foremost:  to  develop  an  in- 
tegrated environmental  data  base,  merging 
economic,  social  and  natural  resource  infor- 
mation for  analyses  by  the  IGIS;  and  pro- 
duce a  state-of-the-environment  report  for 
Illinois.  The  environmental  trends  which 
evolve  from  the  analyses  can  be  synthe- 
sized into  a  report  written  for  the  general 
public  that  will  provide  an  overview  of  the 
state's  environment  and  the  implications  for 
human  health,  economical  health,  and 
quality  of  life.  More  importantly,  the  report 
that  results  from  the  analyses  will  help  as- 
sure that  environmental  policy  is  based 
upon  a  comprehensive  picture  of  trends 
and  rate  of  change.  A  more  meaningful 
perspective  should  evolve  as  the  Survey 
and  the  state  work  toward  both  a  healthy 
economy  and  a  healthy  environment. 

Toward  these  goals,  near-term  challen- 
ges for  the  Geological  Survey,  as  one  of 
the  state's  earth  agencies,  include: 

•  Transfer  of  the  high-surface-area 
(HSA)  hydrated  lime  process  to  in- 
dustry 

Continued  development  of  the  HSA  hy- 
drated lime  technology  and  transfer  of  its 
technology  to  the  commercial  market  is  re- 
quired as  rapidly  as  possible  to  increase 
the  use  of  Illinois'  coal  by  utilities,  its  major 
market,  threatened  by  acid-rain-reduction 
goals  that  restrict  sulfur  emissions.  This 
post-combustion  cleaning  process,  devel- 
oped by  the  ISGS'  researchers,  will  in- 
crease the  effectiveness  of  dry-injection 
systems  for  decreasing  sulfur-dioxide  emis- 
sions, having  achieved  superior  sulfur- 
dioxide  removal  results  over  other  hydrates 
tested  (up  to  90  percent  increased  effective- 
ness). 


23 


24 


•  Maintaining  the  marketability  of 
Illinois'  coal  resources 

Programs  to  decrease  sulfur-dioxide  emis- 
sions have  been  well  established  at  the 
ISGS,  including  research  to  decrease  the 
sulfur  and  mineral-matter  content  (pre- 
combustion  cleaning),  research  to  more 
economically  remove  sulfur  dioxide  from 
combustion  gases  such  as  the  lime  hy- 
drate, and  programs  to  encourage  and  aid 
researchers  throughout  the  world  to  help 
solve  problems  associated  with  the  use  of 
Illinois'  coal. 

Through  continued  research,  the  ISGS 
looks  forward  to  breakthroughs  on  liquids 
from  coal  by  means  of  mild  gasification; 
lignin-enhanced  depolymerization  of  coal; 
and  other  projects  needed  to  help  maintain 
viable  markets  for  Illinois'  coal. 

•  Stable  state  funding  for  oil  recovery 
research 

Stable,  long-term  funding  must  be  imple- 
mented to  support  the  state's  share  of  the 
promising  state-federal  cooperative  re- 
search program  on  improved  and  en- 
hanced oil  recovery,  highlighted  in  this 
report. 

•  Stable  state  funding  for  the  IGIS 

Stable,  long-term  funding  must  be  devel- 
oped to  support  the  continued  operation 
and  maintenance  of  the  IGIS  and  to  sup- 
port the  continued  development  of  the 
various  computerized  data  bases  required 
by  its  users. 

•  Groundwater  protection  research 
program 

Continued  research  and  enhanced  financial 
support  is  needed  to  meet  the  mandates  of 
the  Illinois  Groundwater  Protection  Act,  es- 
pecially projects  directed  toward  developing 
an  understanding  of  the  present  quality  of 
groundwater,  to  establish  a  base  line 
against  which  to  compare  any  future 
changes  in  its  quality,  and  to  protect  this 
vital  resource. 

•  Contributions  of  the  ISGS  to  waste 
management  programs 

Greater  efforts  are  needed  to  gain  recogni- 
tion and  use  of  geologic  maps  and  the  GIS 
in  providing  technical  assistance  for  landfill- 
site  screening  as  an  integral  part  of  pro- 
grams in  solid  waste  management  and  to 
recognize  the  continued  need  for  siting 
some  landfills.  Even  if  programs  for  recy- 
cling and  waste  reduction  are  highly  suc- 
cessful, some  waste  will  always  be 
generated. 


•  Funding  for  a  statewide  geologic 
mapping  program 

An  initiative  must  be  implemented  for  a 
fully-funded  program  to  map  the  geology  of 
Illinois  in  the  detail  required  to  respond  to 
modern  needs  for  geological  information. 
Illinois'  program  should  include  a  clear 
authorization  for  the  expenditure  of  at  least 
$1.1  million  per  year  in  1990  dollars,  with  or 
without  matching  funds  from  federal  or 
other  sources. 

Looking  ahead  three  to  five  years, 
longer-term  challenges  to  the  ISGS  include: 

•  Rebuilding  the  infrastructure 

A  program  needs  to  be  implemented  to  find 
and  characterize  the  aggregate  materials 
and  other  industrial  and  metallic  mineral 
resources  that  will  be  required  to  rebuild 
the  crumbling  infrastructure.  Such  informa- 
tion can  be  a  significant  outgrowth  of  the 
geologic  mapping  initiative. 

•  Environmentally  responsible 
development  and  use  of  fossil  fuels 

Research  must  be  continued  on  the  en- 
vironmentally responsible  development  and 
use  of  fossil  fuels  to  sustain  the  economy 
of  southern  Illinois.  While  alternative  fuels, 
like  ethanol  and  hydrogen,  and  alternative 
energy  sources,  like  solar  and  wind  power, 
will  be  an  increasingly  important  part  of  the 
overall  energy  supply  for  the  United  States, 
coal  and  liquid  hydrocarbons  will  continue 
to  be  major  sources  of  energy  for  the  fore- 
seeable future.  Because  no  other  energy 
sources  occur  in  such  a  convenient  form 
and  at  such  a  low  cost,  they  will  continue  to 
be  the  touchstones  against  which  the  eco- 
nomic viability  of  other  energy  sources  will 
be  measured. 

•  Broad-based  research  program  on 
global  climate  change 

A  need  exists  to  develop  a  broad-based, 
integrated,  department-wide  research  pro- 
gram on  global  climate  change  and  its  po- 
tential impacts  on  the  environment  and  the 
economy  of  Illinois.  The  program  should 
not  only  examine  observable  changes  in 
the  climate  and  atmospheric  composition, 
but  it  should  also  examine  the  manner  in 
which  activities  of  industries  in  the  state 
affect  the  climate  and  atmosphere  and 
whether  proposed  remedial  actions  will 
have  an  impact  on  the  accumulation  of 
greenhouse  gases.  The  Department  of 
Energy  and  Natural  Resources  is  uniquely 
equipped  to  carry  out  the  kind  of  full  life- 
cycle  analyses  necessary  to  determine 


whether  a  proposed  energy  conservation 
strategy  or  alternative  fuel  production 
method  is  neutral  or  beneficial  in  terms  of 
reducing  greenhouse-gas  emissions.  The 
potential  impacts  on  Illinois'  biological  diver- 
sity and  groundwater  quality  of  altered 
agronomic  practices  for  purposes  of  bio- 
mass  fuel  production  (derived  from  ferment- 
ing wood  or  agricultural  wastes)  also 
require  close  examination. 

•  Improved  technology  transfer 
program 

A  program  needs  to  be  implemented  to  sig- 
nificantly enhance  the  ability  of  the  ISGS  to 
transfer  its  technologies  and  other  scien- 
tific information  to  the  people  who  need  it. 


Minerals  engineer  Hank  Ehrlinger  monitors  the  12-foot-tall  Deister 
flotation  column  at  the  Applied  Lab.   With  column  flotation,  waste 
material  from  coal  preparation  plants  is  fed  in  slurry  form  into  this 
type  of  column.  A  mixture  of  tiny  air  bubbles,  chemical  reagents 
and  water  is  added.  The  fine  coal  particles  adhere  to  the  air  bub- 
bles and  rise  to  the  top  of  the  column  where  they  are  removed  as  a 
concentrate.    This  method  generates  coal  that  contains  more  than 
13, 000  Btu  per  pound.   The  resulting  coal  slurry  may  be  ideal  for 
use  in  coal  gasification  because  it  is  ready  to  be  made  into  a 
gasifier  feed  slurry  with  little  additional  processing. 


In  addition  to  fundamental  improvements  in 
the  Survey's  abilities  to  provide  computer 
access  to  major  data  files,  staff,  equipment 
and  space  are  required  to  allow  more  fre- 
quent workshops,  seminars  and  other  free 
forums  as  a  means  of  conveying  the  Geo- 
logical Survey's  data  and  research  informa- 
tion to  the  public. 

•  Public  education  on  the  importance 
of  independent  scientific  research 
for  environmental  and  mineral 
resource  issues 

The  Survey  must  speak  for  the  importance 
of  maintaining  a  strong,  politically  inde- 
pendent, non-regulatory  scientific  research 
arm,  capable  of  providing  state  and  local 
governmental  officials  with  unbiased  scien- 
tific analysis  of  the  increasingly  complex  en- 
vironmental and  mineral  resource  issues 
confronting  Illinois. 

Illinois  faces  serious  issues  concerning 
its  water,  land,  energy  and  mineral  resour- 
ces. Can  it  ensure  an  adequate  supply  of 
these  resources?  Are  these  resources 
being  properly  used?  Are  other  uses 
possible  that  would  help  stimulate  the 
economy?  Are  there  new  emerging  tech- 
nologies that  will  help  in  striving  toward 
economic  and  environmental  health? 

Environmental  issues  related  to  the 
management  and  protection  of  Illinois' 
resources  abound — issues  that  involve 
public  safety,  health  and  recreation;  agri- 
culture; and  the  state's  infrastructure.  Is 
groundwater  contamination  a  problem?  If 
so,  where?  How  do  we  protect  our  ground- 
water? How  should  we  manage  wastes  to 
avoid  contamination?  How  do  we  produce 
clean  coal?  Can  natural  or  man-caused 
hazards  be  prevented  or  mitigated?  Can 
we  use  Earth's  processes  and  resources  to 
our  advantage  to  improve  conditions  and 
enhance  the  quality  of  life? 

Responses  to  these  and  similar  ques- 
tions depend  on  continually  increasing 
knowledge  and  understanding  of  our  sur- 
roundings— of  the  structure,  resources  and 
dynamics  of  the  Earth— the  detailed  geol- 
ogy of  this  state.  The  public  and  govern- 
mental officials  require  this  type  of  scientific 
information  to  make  informed  decisions 
about  the  wise  use  of  the  finite  and  pre- 
cious resources — decisions  which  will  af- 
fect the  standard  of  living,  economic  growth 
health  and  safety  of  Illinois'  residents  and 
can  have  an  impact  on  the  nation  as  well. 
To  this  end,  the  ISGS  is  mandated  to  pro- 
vide the  geologic  knowledge  and  informa- 
tion to  help  answer  such  questions. 


25 


Writer/Editor:  Sue  Muckensturm 
Graphic  Designer:  Sandra  Stecyk 
Photographer:  Joel  Dexter 


)  printed  on  recycled  paper 

Printed  by  authority  of  the  State  of  Illinois/1992/3500